Gas shale potential of the Early Jurassic Gordondale Member, Northeastern British Columbia

Daniel Ross, Department of Geological Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC, V6T 1Z4, Canada, E mail: [email protected]

To assess gas shale resources, methane adsorption capacities of Jurassic Gordondale samples from the Peace River district (northeastern British Columbia) were investigated.  The Early Jurassic Gordondale Member is an organic-rich, fine-grained mudrock and as such, is considered a potential gas shale target.  Sorbed gas capacities of moisture-equilibrated samples increases with total organic carbon content (TOC) over a range of 0.5 – 14 wt%.  Methane adsorption capacities range from 0.05 cc/g to over 2 cc/g in organic-rich zones (at 6.5 MPa and 30 ⁰C).  Moisture plays a significant role in the sorption of gases on Gordondale samples.  Although a general decrease of methane adsorption with increasing moisture was observed, no direct relationship could be established between moisture and gas capacity, suggesting moisture has a greater importance than purely a competitor for methane adsorption sites.  Pores and pore throats are likely blocked by moisture rendering many adsorption sites inaccessible to methane.  Twenty to eighty percent of total gas storage is free gas (intergranular porosity), ranging from 0.1 – 1.3 cc/g.  Total gas-in-place ranges from 1 – 24 BCF/section.  The greatest potential for gas production is in zones elongate NNW-SSE, associated with organic carbon concentrations.  To the south-west of the study area (93-P-5), isolated TOC enrichments (up to 20 wt%), thickness, maturity and fracture-potential improve the gas shale potential in this region making it a prime gas exploration target.